medwireNews: The final overall survival (OS) results of the IMpassion130 trial continue to support the first-line use of atezolizumab plus nab-paclitaxel in PD-L1-expressing patients with metastatic triple-negative breast cancer (TNBC).
These findings follow on from a previous analysis showing significantly improved progression-free survival with the addition of the PD-L1 inhibitor to nab-paclitaxel both in the PD-L1-positive and overall population of the phase 3 trial.
Reporting the current analysis at the ESMO Virtual Congress 2020, Leisha Emens (UPMC Hillman Cancer Center, Pittsburgh, Pennsylvania, USA) noted that “the overall survival boundary for statistical significance was not crossed in the intention-to-treat [ITT] population, which precluded further formal testing in the PD-L1 immune cell-positive group.”
Leisha Emens summarizes the IMpassion130 trial and comments on the differences with the IMpassion131 study (2:19)
However, the OS improvement in the PD-L1-positive patients with the addition of atezolizumab was “clinically meaningful,” she said, adding that the data “support a positive benefit to risk profile for the combination of atezolizumab and nab-paclitaxel as first-line therapy” in these patients.
In the ITT population, at a median follow-up of 18.8 months, there was no significant difference in OS between the 451 participants who were randomly assigned to receive atezolizumab alongside nab-paclitaxel and their 451 counterparts who instead received placebo plus the taxane, with comparable medians of 21.0 versus 18.7 months, and 3-year OS rates of 28% versus 25%.
By contrast, median OS was longer with atezolizumab versus placebo in the PD-L1-positive population, at 25.4 and 17.9 months, respectively, and a hazard ratio for death of 0.67. The corresponding OS rates at the 3-year mark were 36% and 22%.
With regard to the safety profile, patients in the atezolizumab group had higher rates of grade 3–4 treatment-related adverse events (AEs; 42 vs 30%), treatment-related serious AEs (13 vs 7%), and AEs leading to treatment discontinuation (19 vs 8%) than those in the placebo group.
But Emens highlighted that “in general, treatment withdrawal was related to nab-paclitaxel and driven by neuropathy.”
Atezolizumab-treated patients also had a higher incidence of immune-related AEs than those given placebo (59 vs 42%), but the presenter noted that “these were generally of low grade and easily managed, and typically did not result in discontinuation of atezolizumab.”
Emens therefore summarized that “the safety profile was consistent with those of the individual treatment components and no new safety signals were identified.”
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